Cold sintering: A promising in situ resource utilisation strategy to densify lunar regolith simulants for construction applications

Sintering lunar regolith simulants as building materials is an effective method to establish long-term lunar bases. However, the high energy consumption of conventional thermal sintering is a challenge for energy-scarce lunars. The cold sintering process (CSP), which densifies ceramics with the assistance of transient solvent, offers a solution to overcome the aforementioned problems. Utilizing the CSP at 150 degrees C, 200 MPa, and 15 wt% 10 mol NaOH for 90 min, the density and compressive strength of the samples reached 2.44 g/cm3 and 207 MPa, respectively. The energy consumption of CSP equipment is only 0.86 kW & sdot;h, which is 6.66 times lower than that of conventional thermal sintering (5.73 kW & sdot;h). Furthermore, the compressive strength of the samples after three cool-heat cycles temperature between -196 degrees C and 150 degrees C was 205 MPa, indicating that the samples maintained high reliability in a simulated lunar environment. This excellent performance is attributed to the NaOH solution dissolving the oxide clusters on the particle surface, and the precipitation-generated glass phase connecting adjacent particles, making the particles consolidated and densified. Therefore, the cold sintering process presents promising prospects for the energy-efficient fabrication of lunar construction materials with excellent mechanical strength and durability.